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Journal Articles

Numerical techniques for parallel dynamics in electromagnetic gyrokinetic Vlasov simulations

Maeyama, Shinya; Ishizawa, Akihiro*; Watanabe, Tomohiko*; Nakajima, Noriyoshi*; Iio, Shunji*; Tsutsui, Hiroaki*

Computer Physics Communications, 184(11), p.2462 - 2473, 2013/11

 Times Cited Count:13 Percentile:29.29(Computer Science, Interdisciplinary Applications)

Journal Articles

Ripple loss of alpha particles in a low-aspect ratio tokamak reactor

Tani, Keiji*; Nishio, Satoshi; Tobita, Kenji; Tsutsui, Hiroaki*; Mimata, Hideyuki*; Iio, Shunji*; Aoki, Takayuki*

Denki Gakkai Rombunshi, A, 129(9), p.569 - 574, 2009/09

Studies on the loss of fusion produced alpha particles enhanced by toroidal field (TF) ripple in a low-aspect-ratio tokamak reactor (VECTOR) have been made by using an orbit-following Monte-Carlo code. In actual TF coil systems, the ripple loss of alpha particles is strongly reduced as the aspect ratio becomes low (the power loss is proportional to A$$^{8.8}$$ for A more than 2.5) and the reduction of the number of TF coils results in a large amount of ripple losses even in a low-aspect-ratio tokamak.

Journal Articles

Numerical study of the ripple resonance diffusion of alpha particles in tokamaks

Mimata, Hideyuki*; Tani, Keiji*; Tsutsui, Hiroaki*; Tobita, Kenji; Iio, Shunji*; Shimada, Ryuichi*

Plasma and Fusion Research (Internet), 4, p.008_1 - 008_8, 2009/04

The energy dependence of the diffusion coefficients of alpha particles in rippled magnetic fields of tokamaks are numerically investigated with an orbit following Monte Carlo code. The diffusion coefficients are enhanced around the ripple resonance energy while they are reduced and has a minimum near the resonance energy, and hence they have an M-shaped dependence on the energy. The ripple resonance is caused by a radial change of the toroidal precession of banana particles, and creates islands in the phase space related with the toroidal and poloidal angles. Since the particles outside the separatrix mainly contribute to the diffusion, the M-shaped energy dependence is explained by both island structure and initial distribution of particles in the phase space. Such a ripple resonant diffusion is dominant for fusion-produced alpha particles in the slowing down process.

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 22

Takenaga, Hidenobu; Ogawa, Yuichi*; Takizuka, Tomonori; Yagi, Masatoshi*; Yamada, Hiroshi*; Sakamoto, Yoshiteru; Toi, Kazuo*; Fukuda, Takeshi*; Fukuyama, Atsushi*; Fujita, Takaaki; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 84(7), p.465 - 467, 2008/07

no abstracts in English

Journal Articles

Response of fusion gain to density in burning plasma simulation on JT-60U

Takenaga, Hidenobu; Kubo, Hirotaka; Sueoka, Michiharu; Kawamata, Yoichi; Yoshida, Maiko; Kobayashi, Shinji*; Sakamoto, Yoshiteru; Iio, Shunji*; Shimomura, Koji*; Ichige, Hisashi; et al.

Nuclear Fusion, 48(3), p.035011_1 - 035011_6, 2008/03

 Times Cited Count:2 Percentile:89.78(Physics, Fluids & Plasmas)

A burning plasma simulation scheme has been developed with consideration for temperature dependence of the DT fusion reaction rate in JT-60U. The heating power for the simulation of alpha particle heating was calculated using real-time measurements of density and ion temperature. Response of a simulated fusion gain to the density was investigated in this scheme with constant heating power for the simulation of external heating, in order to understand burn controllability by the fuel density in a fusion reactor. When temperature dependence of the fusion reaction rate was assumed as square of ion temperature, density dependence of the simulated fusion gain stronger than square of density was observed. Transport analysis using a 1.5 dimension transport code indicated that the strong density dependence is induced due to both change in a confinement improvement factor and change in a pressure profile.

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 20

Fujita, Takaaki; Fukuda, Takeshi*; Fukuyama, Atsushi*; Sakamoto, Yoshiteru; Toi, Kazuo*; Ogawa, Yuichi*; Takenaga, Hidenobu; Takizuka, Tomonori; Yagi, Masatoshi*; Yamada, Hiroshi*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 84(1), p.70 - 72, 2008/01

no abstracts in English

Journal Articles

Burn control simulation experiments in JT-60U

Shimomura, Koji*; Takenaga, Hidenobu; Tsutsui, Hiroaki*; Mimata, Hideyuki*; Iio, Shunji*; Miura, Yukitoshi; Tani, Keiji; Kubo, Hirotaka; Sakamoto, Yoshiteru; Hiratsuka, Hajime; et al.

Fusion Engineering and Design, 82(5-14), p.953 - 960, 2007/10

 Times Cited Count:2 Percentile:79.49(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Report of meetings of ITPA (International Tokamak Physics Activity), 19

Sasao, Mamiko*; Kusama, Yoshinori; Kawano, Yasunori; Kawahata, Kazuo*; Mase, Atsushi*; Sugie, Tatsuo; Fujita, Takaaki; Fukuda, Takeshi*; Fukuyama, Atsushi*; Sakamoto, Yoshiteru; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 83(9), p.779 - 782, 2007/09

This is a report of highlights from 2007 spring meetings of seven Topical Groups (TG) of International Tokamak Physics Activity (ITPA). In each meeting, high priority issues in physics of International Thermonuclear Experimental Reactor (ITER) and other burning plasma experiments have been discussed and investigated. Twenty-seven scientists from Japan have participated in those meetings. Dates and places of the meetings are shown below. (1) Diagnostics TG: 26-30 March, Princeton (USA), (2) Transport Physics TG: 7-10 May, Lausanne (Switzerland), (3) Confinement Database and Modeling TG: 7-10 May, Lausanne (Switzerland), (4) Edge Pedestal Physics TG: 7-10 May, Garching (Germany) (5) Steady State Operation TG: 9-11 May, Daejeon (South Korea), (6)MHD TG: 21-24 May, San Diego (USA), (7) Scrape-off-layer and Divertor Physics TG: 7-10 May, Garching (Germany).

Journal Articles

Magnetic fusion energy studies in Japan

Ogawa, Masao*; Iio, Shunji*; Komori, Akio*; Kawahata, Kazuo*; Kaneko, Osamu*; Inoue, Takashi; Kamada, Yutaka

Nuclear Instruments and Methods in Physics Research A, 577(1-2), p.30 - 36, 2007/07

 Times Cited Count:4 Percentile:62.18(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Burn control study using burning plasma simulation experiments in JT-60U

Takenaga, Hidenobu; Miura, Yukitoshi; Kubo, Hirotaka; Sakamoto, Yoshiteru; Hiratsuka, Hajime; Ichige, Hisashi; Yonekawa, Izuru*; Kawamata, Yoichi; Iio, Shunji*; Sakamoto, Ryuichi*; et al.

Fusion Science and Technology, 50(1), p.76 - 83, 2006/07

 Times Cited Count:3 Percentile:73.3(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Report of ITPA (International Tokamak Physics Activity) meetings, 17

Asakura, Nobuyuki; Kato, Takako*; Nakano, Tomohide; Takamura, Shuichi*; Tanabe, Tetsuo*; Iio, Shunji*; Nakajima, Noriyoshi*; Ono, Yasushi*; Ozeki, Takahisa; Takechi, Manabu; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 82(7), p.448 - 450, 2006/07

no abstracts in English

Journal Articles

Confinement of alpha particles in a low-aspect-ratio tokamak reactor

Tani, Keiji; Tobita, Kenji; Iio, Shunji*; Tsutsui, Hiroaki*; Nishio, Satoshi; Aoki, Takayuki*

Denki Gakkai Rombunshi, A, 125(11), p.938 - 942, 2005/11

Studies on the loss of fusion produced alpha particles enhanced by toroidal field (TF) ripple in a low-aspect-ratio tokamak reactor (VECTOR) have been made by using an orbit-following Monte-Carlo code. The ripple loss is strongly reduced as the aspect ratio becomes low. Consequently, alpha particles are well confined in VECTOR. Thanks to the good confinement of alphas in a low-aspect-ratio system, the number of TF coils can be reduced to about 6, one half of the original VECTOR, by installing cooling systems near the outer edge of plasma and making allowances for about 30% increase in the bore diameter of TF coils.

Journal Articles

Report of ITPA (International Tokamak Physics Activity) meeting, 15

Ninomiya, Hiromasa; Asakura, Nobuyuki; Kato, Takako*; Takamura, Shuichi*; Tanabe, Tetsuo*; Nakano, Tomohide; Iio, Shunji*; Ozeki, Takahisa; Ono, Yasushi*; Sugihara, Masayoshi; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 81(11), p.960 - 961, 2005/11

no abstracts in English

Journal Articles

Report of ITPA (International Tokamak Physics Activity) meeting, 13

Kawano, Yasunori; Kawahata, Kazuo*; Kusama, Yoshinori; Sasao, Mamiko*; Sugie, Tatsuo; Mase, Atsushi*; Asakura, Nobuyuki; Kato, Takako*; Takamura, Shuichi*; Tanabe, Tetsuo*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 81(2), p.128 - 130, 2005/02

no abstracts in English

Journal Articles

Numerical simulation on current spike behaviour of JT-60U disruptive plasmas

Takei, Nahoko; Nakamura, Yukiharu; Tsutsui, Hiroaki*; Yoshino, Ryuji; Kawano, Yasunori; Ozeki, Takahisa; Tobita, Kenji; Iio, Shunji*; Shimada, Ryuichi*; Jardin, S. C.*

Plasma Physics and Controlled Fusion, 46(12), p.1815 - 1830, 2004/12

 Times Cited Count:1 Percentile:96.79(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Confinement of alpha particles in a low aspect ratio tokamak reactor

Tani, Keiji; Tobita, Kenji; Nishio, Satoshi; Iio, Shunji*; Tsutsui, Hiroaki*; Aoki, Takayuki*

Purazuma, Kaku Yugo Gakkai-Shi, 80(11), p.931 - 934, 2004/11

Studies were made on ripple losses of fusion produced alpha particles in a low-aspect-ratio tokamak reactor (VECTOR) by using an orbit-following Monte-Carlo code. Alpha particles are well confined in VECTOR. In a low-aspect-ratio tokamak, the dependence of ripple losses on the number of toroidal-field (TF) coils N is very weak. Assuming a toroidal peaking factor of 2 for the heat load due to loss particles, about 1.5% and 1.0% of TF ripple at the outer edge of plasma might be allowable for the first wall with and without cooling system, respectively. In both cases, the number of TF-coils can be reduced to about 4.

Journal Articles

10th report of Meeting on ITPA

Asakura, Nobuyuki; Iio, Shunji*; Ozeki, Takahisa; Ono, Yasushi*; Kato, Takako*; Kawano, Yasunori; Sugihara, Masayoshi; Takamura, Shuichi*; Tanabe, Tetsuo*; Nakajima, Noriyoshi*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 80(7), P. 642, 2004/07

no abstracts in English

Journal Articles

Progress in physics and technology developments for the modification of JT-60

Tamai, Hiroshi; Matsukawa, Makoto; Kurita, Genichi; Hayashi, Nobuhiko; Urata, Kazuhiro*; Miura, Yushi; Kizu, Kaname; Tsuchiya, Katsuhiko; Morioka, Atsuhiko; Kudo, Yusuke; et al.

Plasma Science and Technology, 6(1), p.2141 - 2150, 2004/02

 Times Cited Count:2 Percentile:92.83(Physics, Fluids & Plasmas)

The dominant issue for the the modification program of JT-60 (JT-60SC) is to demonstrate the steady state reactor relevant plasma operation. Physics design on plasma parameters, operation scenarios, and the plasma control method are investigated for the achievement of high-$$beta$$. Engineering design and the R&D on the superconducting magnet coils, radiation shield, and vacuum vessel are performed. Recent progress in such physics and technology developments is presented.

Journal Articles

TSC simulation of ITB crash and following disruption dynamics on JT-60U high-$$beta$$ reversed shear plasmas

Takei, Nahoko; Nakamura, Yukiharu; Kawano, Yasunori; Tsutsui, Hiroaki*; Ozeki, Takahisa; Tobita, Kenji; Sugihara, Masayoshi; Iio, Shunji*; Shimada, Ryuichi*; Jardin, S. C.*

Europhysics Conference Abstracts, 28G, 4 Pages, 2004/00

no abstracts in English

Journal Articles

Axisymmetric MHD simulation of ITB crash and following disruption dynamics of tokamak plasmas with high bootstrap current

Takei, Nahoko; Nakamura, Yukiharu; Kawano, Yasunori; Tsutsui, Hiroaki*; Ozeki, Takahisa; Tobita, Kenji; Sugihara, Masayoshi; Iio, Shunji*; Shimada, Ryuichi*; Jardin, S. C.*

Journal of Plasma and Fusion Research SERIES, Vol.6, p.554 - 557, 2004/00

no abstracts in English

48 (Records 1-20 displayed on this page)